SPATS TASK 1-650 - REVIEW OF UPDATES TO EMISSION CURVES FOR NON-CONVENTIONAL ICE AND ULTRA-LOW EMISSION VEHICLES
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles Task in: Production of updated emission curves for NTM and WebTAG _ _ Report for Department for Transport DFT: 1-650 P04102073 through Arup, ref no: 268492-13 ED 11852 | ULEV evidence review, Issue 3 | Date 26/03/2019 Ricardo in Confidence
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | i Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 Customer: Contact: Department for Transport John Norris Ricardo Energy & Environment Gemini Building, Harwell, Didcot, OX11 0QR, United Kingdom t: +44 (0) 1235 75 3685 e: John.Norris@ricardo.com Ricardo-AEA Ltd is certificated to ISO9001 and ISO14001 Customer reference: DfT: 1-650 P04102073 Through Arup; Arup ref no: 268492-13 Confidentiality, copyright & reproduction: This report is the Copyright of Department for Transport.
It has been prepared by Ricardo Energy & Environment, a trading name of Ricardo-AEA Ltd, under contract to Department for Transport dated 03/09/2018. The contents of this report may not be reproduced in whole or in part, nor passed to any organisation or person without the specific prior written permission of Department for Transport. Ricardo Energy & Environment accepts no liability whatsoever to any third party for any loss or damage arising from any interpretation or use of the information contained in this report, or reliance on any views expressed therein.
Author: John Norris (Ricardo Energy & Environment) Approved By: Tim Murrells Date: 26 March 2019 Ricardo Energy & Environment reference: Ref: ED11852- ULEV evidence review, Issue 3
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | ii Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 Table of contents 1 Introduction ___ 2
1.1 Overview ___ 2
1.2 Scope and overview of the methodology ___ 2
2 Résumé of data and method tables used in the original report ___ 4
2.1 Overview of the core data sources ___ 4
2.2 Summary of key data sources used ___ 9
3 LDV - Detailed consideration of data available ___ 10
3.1 Emission models ___ 10
3.1.1 COPERT 10 3.1.2 Swiss-German-Austrian Handbook of Emission Factors (HBEFA ___ 11
3.1.3 PHEM and other Vehicle simulation models ___ 11
3.2 Manufacturers’ data ___ 11
3.2.1 VCA new vehicle emissions database ___ 11
3.2.2 Change in type approval process ___ 12
3.3 Utility factor ___ 13
3.4 Independently gathered emissions data ___ 14
3.4.1 Laboratory testing ___ 14
3.4.2 PHEM simulation data and PEMS data from Emission Analytics ___ 15
3.4.3 RDE measurements using PEMS ___ 15
3.4.4 Remote sensing data ___ 15
4 HDV - Detailed consideration of data available ___ 16
4.1 Overview ___ 16
4.2 Significance of various ultra-low emission HDV in the fleet ___ 16
4.2.1 Dedicated methane fuelled HGV ___ 16
4.2.2 Diesel/methane dual fuelled HGV ___ 17
4.2.3 Battery electric and hydrogen fuelled HGV ___ 18
4.2.4 Ultra-low emission buses (hybrids, battery electric, methane and hydrogen ___ 18
5 Conclusions .
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | iii Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 5.1.1 Recommendations for LDV ___ 21
5.1.2 Recommendations for HDV ___ 21
5.2 Priorities of recommendations . 22
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 1 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 Glossary of abbreviations ANPR Automatic Number Plate Recognition BEV Battery Electric Vehicle CI Compression Ignition COPERT Software tool for calculating pollutant emissions from road transport DfT UK Department for Transport ERMES European Research on Mobile Emission Sources EV Electric Vehicle FCEV Fuel Cell Electric Vehicle GSR Gas Substitution Rate HBEFA HandBook of Emission Factors HDV Heavy Duty Vehicle (both HGVs and buses/coaches) HEV Hybrid Electric Vehicle HGV Heavy Goods Vehicle ICE Internal Combustion Engine ITS Leeds Institute of Transport Studies at Leeds University LDV Light duty vehicle (both passenger cars and LGV, see below) LGV Light Goods Vehicle NAEI National Atmospheric Emissions Inventory NTM National Transport Model PC Passenger cars PEMS Portable Emissions Monitoring Systems PHEM Technical University of Graz’s vehicle and powertrain simulation model PHEV Plug-in Hybrid Electric Vehicle PM Particulate matter SI Spark Ignition TfL Transport for London TRL Transport Research Laboratory UF Utility factor ULEV Ultra-Low Emission Vehicle VCA Vehicle Certification Agency VERSIT Instantaneous traffic emissions model developed by TNO WebTAG DfT Web-based Transport Analysis Guidance WLTC Worldwide harmonised Light vehicles Test Cycle WLTP Worldwide harmonised Light vehicles Test Procedure
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 2 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 1 Introduction 1.1 Overview DfT require an update to the speed-emission factor and fuel consumption curves in a specified format for use in the NTM and WebTAG consistent with the exhaust emission factors in the European COPERT 5 model, now used in the compilation of the UK’s National Atmospheric Emissions Inventory (NAEI) on behalf of Defra and BEIS (http://naei.beis.gov.uk/) and in national air quality modelling under the MAAQ contract for Defra.
This includes modelling that underpinned the UK’s Plans for reducing roadside nitrogen dioxide concentrations. The update to these speed-emission curves has been reported separately.
The updated emission curves provided for the NTM and WebTAG are restricted to vehicles running on conventional petrol and diesel engines. In this separate project we revisit evidence on speed-emission curves for non-conventional Internal Combustion Engine (ICE) and other ultra-low emission (ULEV) vehicles developed by Ricardo in 2015 in a report “Speed emission/energy curves for ultra-low emission vehicles”. This project comprises a short scoping study that will examine whether there is sufficient new evidence to merit revisiting and possibly updating the emission curves for these vehicles.
The conclusions from this provides DfT with the basis for a fuller discussion to decide whether an update of the 2015 curves is appropriate.
1.2 Scope and overview of the methodology The vehicles and technologies which are covered by the project are shown in Table 1. For each vehicle/technology type except buses, speed emission/energy curves were previously developed for fuel or energy use, and CO2, NOx and PM10 emissions. Table 1 Low Emission Vehicles in scope for this review Vehicle Type Fuel/Technology Type Cars Petrol Hybrid Electric Vehicle (Petrol HEV) Diesel Hybrid Electric Vehicle (Diesel HEV) Petrol Plug-in Hybrid Electric Vehicle (Petrol PHEV) Diesel Plug-in Hybrid Electric Vehicle (Diesel PHEV) Battery Electric Vehicle (BEV) Fuel Cell Electric Vehicle (FCEV) Light Goods Vehicles Petrol Hybrid Electric Vehicle Diesel Hybrid Electric Vehicle Petrol Plug-in Hybrid Electric Vehicle Diesel Plug-in Hybrid Electric Vehicle Battery Electric Vehicle Fuel Cell Electric Vehicle Rigid Heavy Goods Vehicles Biomethane/ Natural Gas Vehicle Dual Fuel Diesel & Biomethane/ Natural Gas Vehicle Battery Electric Vehicle (3.5t -12t GVW only)
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 3 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 Vehicle Type Fuel/Technology Type Articulated Heavy Goods vehicles Biomethane/ Natural Gas Vehicle Dual Fuel Diesel & Biomethane/ Natural Gas Vehicle Buses (not included in the original 2015 review) Biomethane/ Natural Gas Vehicle Hybrid buses Battery Electric buses Fuel Cell Electric buses Buses are a new vehicle type introduced in this study because of their increasing importance, although they were not within the scope of the 2015 study.
This report starts with a résumé of the data and methodologies used in the earlier 2015 report, using summary data Tables 5, 6 and 7 of the earlier report. From these a complete list of key data sources that were used is drawn up, and coloured to highlight those sources where significant new evidence has become available. The new evidence for these sources is then systematically discussed in the following chapters with Chapter 3 covering light duty vehicles, and Chapter 4 covering heavy duty vehicles, including buses.
- Existing emissions models
- Manufacturers’ type approval data
- Literature results on real world emissions
- Simulation data using the PHEM model
- PEMS data from vehicle tests in the UK In terms of quantities of data for different vehicle categories, the 2015 study used the speed related emission factor curves for some ULEV for which there were considerable data, to derive the speed related emission factor curves for others. Figure 1 below summarises these relationships for light duty vehicles.
Figure 1 Relationship between data sources and ULEV light duty vehicle categories for curve fitting
- Green cells denote core technologies for which a substantial quantity of emissions data existed and which comprise the starting data from which other emission factors are extrapolated;
- Red cells denote technologies whose emissions performance was extrapolated from the core technologies;
- Mustard coloured circles contain key factors/assumptions involved in the extrapolations. Figure 2 summarises what data sources were used for heavy duty vehicles. (The section numbers refer to subsections in the original 2015 report.) It shows that for HDV there is much less primary data than was the case for LDV and curves for BEV vans were used to estimate energy curves for small HGVs. We cite some studies Ricardo undertook on methane fuelled vehicles for the DfT. The gas substitution rate (GSR), i.e. the amount of diesel substituted by methane, is the other primary input parameter determining the emissions from dual fuel diesel/methane HGV.
Figure 2 Relationship between data sources and ULEV heavy duty vehicle categories for curve fitting Legend: green is new data, mustard is scaling factors, orange are derived emission curves. In more detail, the following two tables summarise the methodology used to generate the speed related emission functions for light duty vehicles. An analogous table for HDVs is given in Table 4.
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 6 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 Table 2 Summary of curve generation for cars (Table 5 of 2015 study) Petrol HEV Diesel HEV BEV Petrol PHEV Diesel PHEV Fuel Cell EV NOx Curve data PHEM data for HEV and ICE, normalised to COPERT PEMS data COPERT scaling for Euro 6 N/A Extrapolated from HEV and BEV data using utility factor Extrapolated from HEV and BEV data using utility factor N/A Validation data PEMS data Manufacturers’ data Manufacturers’ data N/A Manufacturers’ data Manufacturers’ data N/A Vehicle categories 1 vehicle size Euro 5 and 6 1 vehicle size Euro 5 and 6 N/A 1 vehicle size 3 utility factors Euro 6 1 vehicle size 3 utility factors Euro 6 N/A PM Curve data No data, assume HEV same as COPERT ICE No data, assume HEV same as COPERT ICE N/A Extrapolated from HEV and BEV data using utility factor Extrapolated from HEV and BEV data using utility factor N/A Validation data None None N/A Manufacturers’ data Manufacturers’ data N/A Vehicle categories 1 vehicle size Euro 5 and 6 1 vehicle size Euro 5 and 6 N/A 1 vehicle size 3 utility factors Euro 6 1 vehicle size 3 utility factors Euro 6 N/A CO2/Energy Curve data PHEM data for HEV and ICE, normalised to TRL factors PEMS data TRL data for scaling to Euro 6 PHEM data Single speed curve Extrapolated from HEV and BEV data using utility factor Extrapolated from HEV and BEV data using utility factor Extrapolated from BEV using H2 conversion factor based on manufactures data.
Validation data PEMS data Manufacturers’ data Manufacturers’ data Manufacturers’ data Manufacturers’ data Manufacturers’ data None Vehicle categories 3 vehicle sizes, same as COPERT Euro 5 and 6 1 vehicle size Euro 5 and 6 3 vehicle sizes, scaled based on mass 3 vehicle sizes related to HEV/BEV sizes 3 utility factors Euro 6 3 vehicle sizes related to BEV sizes 3 utility factors Euro 6 1 vehicle size
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 7 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 Table 3 Summary of curve generation for vans (Table 6 of 2015 study) Petrol HEV Diesel HEV BEV Petrol PHEV Diesel PHEV Fuel cell EV NOx Curve data Same as car petrol HEV Scaled to diesel car using same ratio as ICE diesel to van from TRL data N/A Same as car petrol PHEV Extrapolated from HEV and BEV data using utility factor N/A Validation data None None N/A None None N/A Vehicle categories 1 size Euro 6 3 sizes Euro 6 N/A 1 size 3 utility factors Euro 6 3 sizes 3 utility factors Euro 6 N/A PM Curve data Same as car petrol HEV Scaled to diesel car using same ratio as ICE diesel to van from TRL data N/A Same as car petrol PHEV Extrapolated from HEV and BEV data using utility factor N/A Validation data None None N/A None None N/A Vehicle categories 1 size Euro 6 3 sizes Euro 6 N/A 1 size 3 utility factors Euro 6 3 sizes 3 utility factors Euro 6 N/A CO2/Energy Curve data Same as car petrol HEV Scaled to diesel car using same ratio as ICE diesel to van from TRL data Scaled to car HEV by weight Same as car petrol PHEV Extrapolated from HEV and BEV data using utility factor Extrapolated from BEV using H2 conversion factor based on manufactures data Validation data None None Manufacturers’ data None None None Vehicle categories 1 size Euro 6 3 sizes Euro 6 3 sizes 1 size 3 utility factors Euro 6 3 sizes 3 utility factors Euro 6 3 sizes
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 8 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 Table 4 Summary curve generation for HGVs (Table 7 of 2015 study) Dedicated gas-fuelled rigid HGV Dedicated gas-fuelled artic HGV Dual fuel rigid HGV Dual fuel artic HGV Electric rigid HGV NOx Curve data Test data from DfT Methane slip project Extrapolate from dedicated rigid HGV Infer from test data from DfT methane slip project and low carbon truck trial Infer from test data from DfT methane slip project and low carbon truck trial N/A Validation data Existing Ricardo-AEA nonspeed dependent emission factors Existing Ricardo-AEA nonspeed dependent emission factors Literature Literature N/A Vehicle categories 2 rigid truck GVWs Euro V and Euro VI Single articulated truck GVW Euro V and Euro VI 2 rigid truck GVW Euro V and Euro VI 2 rigid truck GVW Euro V and Euro VI N/A PM Curve data Existing Ricardo-AEA nonspeed dependent emission factors Extrapolate from dedicated rigid HGV Same as existing ICE diesel curve Same as existing ICE diesel curve N/A Validation data None Existing Ricardo-AEA nonspeed dependent emission factors Literature Literature N/A Vehicle categories 2 rigid truck GVWs Euro V and Euro VI Single articulated truck GVW Euro V and Euro VI 2 rigid truck GVW Euro V and Euro VI 2 rigid truck GVW Euro V and Euro VI N/A CO2/Energy Curve data Test data from DfT Methane slip project Extrapolate from dedicated rigid HGV Infer from test data from DfT methane slip project and low carbon truck trial Infer from test data from DfT methane slip project and low carbon truck trial Extrapolate from Class 3 BEV van Validation data Existing Ricardo-AEA nonspeed dependent emission factors Existing Ricardo-AEA nonspeed dependent emission factors Literature Literature Literature Vehicle categories 2 rigid truck GVWs Single articulated truck GVW 2 rigid truck GVW Single articulated truck GVW 2 rigid truck GVWs
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 9 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 2.2 Summary of key data sources used For the original study the key data sources used to assess, derive and validate the emissions curves reported are summarised in Table 5. The right-hand column indicates where new data are available in relation to each data source since the 2015 study was undertaken.
Table 5 Key data sources used to assess, derive and validate the emissions curves in the 2015 study For light duty vehicles Data type Data source Availability of new data Models COPERT 4 (v10/11) Moderate new data Handbook of Emission Factors (HB EFA) v3.1 Revised Passenger and Heavy duty Emissions Model (PHEM No new data Other hybrid vehicle simulation models Moderate new data Manufacturers data VCA new car CO2 and emissions database Much new data PEMS measurements including for RDE Much new data Other studies Utility Factor Much new data TRL factors No new data Quantification of real driving emissions (RDE) Much new data Independently gathered emissions data Much new data1 For heavy duty vehicles Data type Data source Availability of new data Research studies DfT Methane slip test data No new data Existing Ricardo non-speed dependent emission factors Revised Dedicated rigid HGV PM & NOx emission factors Revised Low carbon truck trial Moderate new data Literature Moderate new data 1 These data include real driving emissions testing and remote sensing
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 10 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 3 LDV - Detailed consideration of data available 3.1 Emission models 3.1.1 COPERT The 2015 study used COPERT 4 (v10/11) for normalising or scaling NOx and PM emissions rates from petrol and diesel hybrid vehicles available from other sources. These emissions curves were then used to derive analogous emission factors for hybrid light commercial vehicles and for plug-in versions of both car and van PHEVs (see Figure 1).
The COPERT road transport hot emission factors database is available as an Excel file. The latest version is COPERT version 5.2.0, which was published in August 20182 . The only LDV ULEV category in Table 1 for which emission factors are available are petrol HEVs (as was the case for the earlier review). However, emission factors for NOx for these hybrids are likely to have been changed. The “EMISIA SA COPERT Versions” site lists the following changes between since COPERT 4 (v10/11) that are pertinent to this study3: COPERT Version Publication date Updates pertinent to this study COPERT v 4.11.4 September 2016 New PC Euro 6 2020+ and LDV Euro 6 2021+ vehicle category Updated NOx emission factors for PC Diesel & LDV Diesel, Euro6 and on.
PC Diesel post Euro 6 LDV Diesel post Euro 5 COPERT v 5.0.1039 September 2016 Updated NOx emission factors for PC Diesel & LDV Diesel, Euro 6 and on. COPERT v 5.0.1067 October 2016 Corrected NOx hot emission parameters for PC Diesel Medium COPERT v 5.2.0 August 2018 Little change pertinent to this study The 2013 guidebook (which gives the emission factors for hybrids used in COPERT 4 (v10) gives emission factors for a single vehicle category (hybrid petrol passenger cars < 1.6 litres) and gives NOx emissions for urban, rural and highway roads. Examination of the COPERT 5.2 emission factors indicates that there are 52 vehicle categories (Euro standard, vehicle type, fuel technology) and speed functions are expressed as a polynomial for, amongst other species, NOx and fuel/energy consumption.
2 COPERT Emission Factor database available from: https://www.eea.europa.eu/publications/emep-eea-guidebook-2016/part-b-secto ralguidance-chapters/1-energy/1-a-combustion/1-a-3-b-i-1/view 3 For details of changes to COPERT see the site: https://www.emisia.com/utilities/copert/versions/
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 11 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 However, although there are a large number of vehicle categories listed, many of the coefficients are the same, i.e. the same polynomial emission factors cover a range of vehicle categories. Notwithstanding, it is clear that the COPERT factors for HEVs have been updated. In their list of future plans, EMISIA say the next expected update is due in December 2018, and among the planned changes are “an update of alternatively fuelled vehicles (LPG, CNG, hybrids, electric).
However, this update has not yet happened (as of February 2019) 3.1.2 Swiss-German-Austrian Handbook of Emission Factors (HBEFA) The 2015 study used some data from the Swiss-German-Austrian Handbook of Emission Factors (HBEFA 3.1). The current version was updated to HBEFA 3.3 on 25th April 2017.
3.1.3 PHEM and other Vehicle simulation models The NOx, PM and CO2/energy emission curves for petrol HEVs in the 2015 study were generated from a petrol HEV PHEM model run specifically for the project. This has not been added to. However, more sophisticated HEV models have been developed. For example, Ricardo have an HEV vehicle simulator. Recent research activities have developed and validated this model. Also, another key model from the ERMES (European Research on Mobile Emissions) group is TNO’s VERSIT+ model.
3.2 Manufacturers’ data 3.2.1 VCA new vehicle emissions database The 2015 study used the 2013 VCA database of car fuel and CO2 emissions data.
The latest version of this database now available was published in August 2017 (no 2018 data are available yet). The numbers of the different ULEV vehicle categories in the databases are summarised in Table 6. Table 6: Vehicles categorised by fuel type and technology Data available in 2013 database Data available in 2017 database Change Passenger cars Petrol HEV 22 models 82 models + 270% Petrol PHEV 6 models 45 models + 650% Diesel HEV 6 models 3 models - 50% Peugeot & Citroen models no longer available Diesel PHEV 1 model 3 models + 300% EVs 12 models 30 models + 150% Vans Petrol HEV None None Petrol PHEV None 1 model Diesel HEV few None Diesel PHEV None None EVs 13 models 4 models
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 12 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 Large increases in the numbers of available petrol HEV and PHEV, and of BEV models have occurred. However, not only do there remain very few diesel HEV and PHEV in the database, but the numbers of available models have reduced. This leads to the important recommendation that hybrid diesel vehicles should be de-emphasised, and arguably should be removed from the emission factors supplied because fleet numbers will be minimal.
For the petrol HEV and PHEV, their type approval CO2 values are in the public domain and could be analysed to obtain current/updates average emissions over the whole regulatory cycle. The data therefore does not provide speed related information but could be used to update/ scale the previously derived curves. It is noted that no analogous 2018 database has yet been published. In part this may be caused by changes in the light duty type approval process. 3.2.2 Change in type approval process At the time of the 2015 study the VCA published two sets of data because light duty vehicles could be type approved to meet either Euro 5 or Euro 6b emissions standards.
The driving cycle for both these emission standards was the NEDC.
More recently new emissions standards have come into force, as summarised below for passenger cars and N1 Class 1 vans. Implementation dates for large N1 vans, Classes 2 and 3 are 12 months later. Implementation date PM and NOx emission standards Driving cycle Other changes Implications for emission factors+ 1/9/2015 All vehicles to meet Euro 6b NEDC Baseline values 1/9/2017 All new models cars and N1 class 1 vans to meet Euro 6d-Temp WLTP RDE becomes mandatory Certification CO2 figures will change 1/9/2018 All vehicles registered to be type approved to Euro 6c NEDC Baseline values 1/9/2019 All vehicles registered to be type approved to Euro 6d-Temp WLTC RDE becomes mandatory Certification CO2 figures will change even for old models The NEDC comprises two driven components and data for a whole vehicle type were given for the two phases, and for their distance weighted average.
Vehicle certification using WLTP involves four driven components, and each vehicle registered will be given its own CO2 emission factor averaged over the whole WLTC, calculated from the vehicle’s configuration (based on its weight, tyres fitted, air drag) and extrapolated from the extremes for the vehicle’s type approval family. It is not known how VCA will report these data. For the annual monitoring of CO2 emissions from passenger cars (and vans) undertaken by the EEA, the database from vehicle registrations is changing from grouping vehicle registrations according to their “type” and recording how many of each vehicle type were registered, to recording individually each vehicle registered.
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 13 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 The reporting of “Vehicles registered in 2015: final data4 ” comprises around 440,000 rows of data and is a 73 MB uncompressed file. For the 2017 data, vehicles are registered following certification using the NEDC and WLTP regulations. The 2017 provisional data (volume 15 of the series) is 1,700 MB uncompressed file that will not load into Excel because it contains more than 1,000,000 rows of data. (It is estimated to contain around 6 million rows of data.
The number of columns has also been expanded to include key WLTP certification data, e.g. vehicle family identification number and WLTP test mass (rather than mass in running order) and CO2 emissions measured over the WLTC. Communications with the EEA indicate that for the 2019 database, where all registrations are recorded using the WLTP regulation, the database will comprise around 15 million rows of data. Therefore, relative to the 2015 study, vehicle certification recording of the Type 1 test of WLTP is generating much new data on CO2 emissions/energy consumption. This will include test data for HEV and PHEV models, over the WLTP, that were not previously available.
However, it may not be trivial to extract these data and use it to develop new speed-emission curves. 3.3 Utility factor For PHEVs their driving can be sub-divided into the fraction driven using mains derived electricity, for which there are no tailpipe emissions, but there is an electric energy requirement, and the fraction where the vehicle behaves like a conventional hybrid vehicle. The utility factor (UF) weights the consumption in each driving mode according to a modelled consumer behaviour that is based on travel survey data. Widely used standardized methods are the European ECE R101 method and the US SAE J2841 method.
The emission factor curves reported in the 2015 study came from the weighting of these two emission factor curves using this function, shown in Figure 3.
EC regulations and the VCA use a very simple UF calculated as follows: UF = electric range/(electric range +25km) This gives the simple curve shown in Figure 3 where the proportion of electric only operation increases as the electric range increases. Since 2015 further evidence has been amassed on the “real world” ratio of the driving using the two modes. The Miles Consultancy has been highlighting discrepancies between the VCA figure and the real world performance of some PHEVs. This was also reported by LowCVP, and made the UK national headlines in November 20185 . In extreme cases this involved PHEVs that were never charged with mains electricity.
Two suggested alternatives have been provided by (chronologically) the International Council on Clean Transportation, and the Joint Research Council of the European Commission6 . The latter paper is entitled: ““Alternative utility factor versus the SAE J2841 standard method for PHEV and BEV applications” was published on 30th September 2018, and is available in the journal Transport Policy. 4 This is in the EEA Report: “Monitoring of CO2 emissions from passenger cars:Data 2015: final data (Volume 12 in this series of reports) 5 Original story available from Miles Consultancy blog https://themilesconsultancy.com/new-analysis-plug-hybrid-car-mpg-emissionsexpectedspark-debate-suitability-fleet-operation/ with further highlighting by LowCVP https://www.lowcvp.org.uk/news,fleet-operator-consultancyfinds-plugin-hybrid-vehicles-are-not-efficient-for-all-types-of-operation_3 706.htm, and then BBC news https://www.bbc.co.uk/news/business-46152853?intlink_from_url=https://www.b bc.co.uk/news/topics/cljev49lzr4t/electriccars&link_location=live-reporting-story 6 ICCT paper available from: https://www.theicct.org/sites/default/files/publications/EU-PHEV_ICCT-Brief ing-Paper_280717_vF.pdf , and EC JRC paper study published in Transport Policy, 68, (2018) 80 – 97.
- Laboratory tests using a chassis dynamometer and real world drive cycles, which is the traditional testing approach;
- Portable Emissions Monitoring Systems (PEMS) where emissions tests are carried out on vehicles in real traffic situations;
- Remote sensing data that uses a static beam projected across a road to analyse tailpipe emissions from passing vehicles.
3.4.1 Laboratory testing These are chassis dynamometer tests using full emissions characterisation. The changes in light duty vehicle type approval processes have meant much recent laboratory emissions testing has been undertaken. Communications with test houses indicate they are over-subscribed with demands for their services outstripping supply. Therefore, there will be much recent laboratory testing undertaken, including for the new ULEV vehicles, as highlighted in Table 6. A key question for generating emissions curves for ULEVs is its accessibility. It is anticipated that anonymised data, in terms of the modal emissions from the chassis dynamometer tests, of ULEVs with 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0 20 40 60 80 100 120 140 160 180 200 Utility factor Electric range, km Prius, PHEV BMW i3 PHEV Current market average
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 15 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 representative emissions over the whole cycle, could be obtained and analysed to generate updated emissions curves. (This would need to be done in such a way so as to maintain client confidentiality.) 3.4.2 PHEM simulation data and PEMS data from Emission Analytics These were important sources of data for the original, 2015 study. However, no new data have been purchased nor analysed since that study.
3.4.3 RDE measurements using PEMS PEMS data are collected on vehicles operating in real traffic on the road.
Whilst they are less repeatable than laboratory tests and will have less detail in terms of emissions monitored, they are a very useful source of data indicating what the performance of technologies might be on the road. The changes in light duty vehicles type approval regulations (Section 3.2.2), and specifically the introduction of Euro 6d-temp mandates the augmenting of the traditional chassis dynamometer testing (the Type 1 emissions test) with real driving emissions (RDE). Implementation dates are 1/9/2017 for new models and for all new passenger cars and N1 Class 1 vans such testing will be required from 1/9/2019.
The regulations specify that the on-the-road driving emissions should be measured on a second-by-second basis, using PEMS (that meet various accuracy and precision specifications). The important consequence for this work is that much more modal emissions data are being collected from ULEVs. Also, the regulations require that such data are publicly available. This provides a rich source of new data from which speed related emission factors for NOx can be derived. However, further work would need to be carried out to establish exactly what data on ULEVs are available and how this data could be used to generate new emission curves.
3.4.4 Remote sensing data Remote sensing allows the collection of emissions data from vehicles as they pass a fixed monitoring point on a road. It is effectively a snap shot of emissions at one location and is matched with automatic number plate recognition (ANPR) data to link emissions to vehicles. It is a good way of collecting emission data from a very large sample of vehicles, albeit under one traffic situation, and is being used to characterise emissions from local traffic. A disadvantage of the technique is that it does not measure absolute emission factors, but ratios in pollutant emissions relative to CO2.
However, since CO2 emission factors are relatively well understood, the technique provides a useful way of showing the range of factors for a given technology and comparing real world pollutant emissions for a range of technologies under a given traffic situation. Some studies have been used to show the ratio in NO2/NOx emissions for different technologies, potentially useful for this project. The 2015 study discussed a number of studies using this approach undertaken by Kings College in London and the Institute of Transport Studies at Leeds University (ITS Leeds). Within these studies a few LEV’s were captured and provide a small but useful snapshot of the emissions of these vehicles operating on the road.
Since the 2015 study Ricardo Energy & Environment have been undertaking remote sensing measurements using the AccuScan RSD 5000 system provided to Ricardo by OPUS RSE. In total over 350,000 measurements have been made. This includes around 100,000 valid vehicle emissions measurements in London as part of The Real Urban Emissions Initiative (TRUE) which seeks to supply cities with data regarding the real-world emissions of their car fleets and equip them with technical information that can be used for strategic decision-making. The TRUE initiative was established by the International Council on Clean Transportation along with the FIA Foundation, Global NCAP, Emissions Analytics, Transport and Environment and the C40 Cities.
The database includes emissions from hybrids, and potentially PHEVs and would be available for Ricardo to use to develop or adjust existing emission curves for these vehicle types. Its analysis could provide comparative emissions data, e.g. comparing emissions from Euro 6b petrol hybrids with their non-hybrid counterparts.
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 16 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 4 HDV - Detailed consideration of data available 4.1 Overview Vehicle categories for which speed related emission functions were generated in the 2015 study are given in Table 1. This is expanded in Table 5 where the availability of new data sources is reviewed in the final column. Generally, whilst some new data have become available there have not been major studies adding to this. So for HDV, this review of evidential data available for generating emission factor curves is structured by considering the ultra-low emission HDV available in the current fleet.
This defines the potential need for such curves. The subsections below give further details on a vehicle category by vehicle category basis.
Because some ULEV vehicle categories, i.e. buses, are now more widely in service, even though they were not considered in the earlier study, Table 7 is expanded to include them. Table 7 HGV technology categories Vehicle fuel Vehicle type Emission-curves that were generated in 2015 study Trucks Dedicated methane Rigid 16 and 26 t CO2, NOx and PM Articulated CO2, NOx and PM Diesel/methane dual fuel Rigid 16 and 26 t CO2, NOx and PM Articulated CO2, NOx and PM Battery electric truck Rigid 3.5 – 7.5 t Energy Rigid 7.5 – 12 t Energy Buses Hybrid City buses Not included in earlier study Dedicated methane City buses Not included in earlier study Battery electric buses City buses Not included in earlier study Fuel cell buses City buses Not included in earlier study 4.2 Significance of various ultra-low emission HDV in the fleet 4.2.1 Dedicated methane fuelled HGV A LowCVP study on the “Emissions testing of Gas Powered Commercial Vehicles”, has been completed and published in January 2017.
The overall view of this study, and consultation with the relatively recently formed LowCVP's Commercial Vehicle Working Group, recommends that the Government: “should continue to support the development of gas vehicle infrastructure and gas-powered vehicles,
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 17 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 particularly dedicated gas, while increasing the supply of low carbon/renewable methane as a sustainable transport fuel in order to realize these benefits.”7 This study does contain some emissions data which are available to Ricardo and could be added to the evidence base included in the generation of emission curves.
In terms of penetration into the fleet, unlike diesel/methane dual fuelled HGV, see the section below, where penetration into the fleet has stalled/reversed, dedicated methane fuelled HGV continue to be seen as viable.
There are large commercial attractions because of the differential in tax between the fuel duty on diesel and methane (around £0.40 per taxed unit when VAT is included). Iveco, who claim to be the methane engine leaders and Scania have both relatively recently announced 13 litre dedicated methane engines, of 345 kW and 300 kW peak power, respectively8 In addition to the largest power units described above, smaller dedicated methane fuelled engines appropriate to powering buses are being manufactured. These are considered in further detail in subsection 4.2.4.
4.2.2 Diesel/methane dual fuelled HGV Dual fuel methane/diesel vehicles retain the existing diesel compression ignition (CI) engine but run using a combination of diesel and methane gas fuels. The diesel provides the ignition source because it auto-ignites, but some (to most) of the power stroke’s energy comes from the combustion of methane. The amount of diesel substituted by methane is called the gas substitution ratio (GSR) and depends on the duty cycle of the vehicle. The need to have some diesel present to provide the ignition source means that under low power conditions little gas is used.
Overall the emissions of dual fuel methane/diesel vehicles are much more similar to their diesel counterparts than the dedicated SI methane vehicles discussed above.
The attraction of dual fuel vehicles is that the basic engine remains unaltered, and in the absence of methane refuelling infrastructure, the vehicle can revert to being a standard diesel vehicle. The principal challenge is adjusting the methane fuelling over the engine’s operational envelop to ensure drivability, but at the same time to meet the Euro VI emission standards, including limits on methane slip for dual fuel vehicles. For dual fuel vehicles, in 2015 there had been very little data. However, data generated by the Low Carbon Truck Demonstration Trial and a LowCVP project on the “Emissions testing of Gas Powered Commercial Vehicles, has since been published.
However, most of the vehicles studies were Euro V compliant after-market conversions.Summarising the key features about the diesel/methane dual fuelled trucks are:
- Most diesel/methane dual fuelled trucks that have been placed on the road were aftermarket conversions;
- The two largest companies involved were Clean Air Power, and Hardstaffs; 7 See LowCVP report on “Emissions testing of gas-powered commercial vehicles”, study for DfT, published January 2017, available from https://assets.publishing.service.gov.uk/government/uploads/system/uploads/ attachment_data/file/581859/emissions-testing-of-gaspowered-commercial-vehicles.pdf 8 See, for example https://www.iveco.com/uk/products/pages/gas-engine-stralis-natural-power-tr uck.aspx and https://www.scania.com/global/en/home/experience-scania/news-and-events/eve nts/2017/latest-gas-engine-designed-for-long-distancetransport.html
- SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 18 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3
- Clean Air Power went into voluntary liquidation in Sept 2015, and was sold to Vayon Holdings Ltd;
- Harstaff too were bought by Vayon Holdings Ltd in Sept 2015;
- Vayon closed Clean Air Power https://www.greencarcongress.com/2016/04/20160405- vayoncap.html ;
- Vayon Hardstaffs creditors meeting occurred in Nov 2016 as Hardstaffs too ceased trading: https://www.thegazette.co.uk/notice/2638898.
Consequently, the principal suppliers of dual fuel vehicles have ceased trading since 2015. There are other companies who undertake aftermarket conversions, modifying pure diesel engines to be dual fuelled (e.g. Prins and G-Volution) but our research has not indicated there are any vehicles that meet Euro VI emissions standards on the market. With regards to vehicle OEMs, rather than aftermarket conversions, Volvo do appear to have a product9 . The overall conclusion from this review of evidence regarding diesel/methane dual fuel trucks is that these vehicles are not being used in significant numbers, and there is no clear route to market, so currently there is no reason to seek to update the emission curves.
Similarly, it is also noted that there do not appear to be diesel/methane dual fuel buses, and so there is no recommendation that emission curves are generated for this vehicle category. 4.2.3 Battery electric and hydrogen fuelled HGV We are not aware of major significant additional data becoming available for this group of ULEV trucks. Moreover, DfT’s “Road to zero” report summarises the current position in its appendices, stating that for both 18 tonne HGV (Figure A4) and 44 tonne HGV (Figure A5) “Electric and hydrogen trucks are not yet market ready, but would offer the most significant GHG and pollutant emission reductions.”.
Therefore, at present it is not suggested that energy consumption (or emissions) data are estimated from available evidence as an immediate priority.
4.2.4 Ultra-low emission buses (hybrids, battery electric, methane and hydrogen) DfT statistics (December 2017) indicate there are around 40,300 buses and coaches in Great Britain, with around 35,000 in England10 . This is shown in Figure 4. Around 10,150 of these are in London (25.2% of the overall total, and 29% of the English total). The DfT statistics do not publish data on the powertrains used for these vehicles. 9 Information on Volvo dual fuel product from https://dieselnet.com/news/2017/10volvo.php 10 DfT bus statistics taken from https://assets.publishing.service.gov.uk/government/uploads/system/uploads/ attachment_data/file/666759/annualbus-statistics-year-ending-march-2017.pdf with further detailed analysis coming from https://www.gov.uk/government/statistical-datasets/bus06-vehicle-stocks-technology-and-equipment#table-bus0602
SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 19 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 Figure 4 Numbers of buses and coaches in Great Britain Transport for London (TfL) operate around 9,550 of London’s buses. The powertrain of these include hybrids, electrics and 8 hydrogen buses, see Figure 511 . This shows how around 30% are hybrid buses, and electric buses are approaching 1% of the fleet. The NAEI already uses data provided by TfL on the proportions of hybrid buses in the fleet and the reductions in emissions they lead to relative to conventional diesel buses.
These are based on emissions measured over a London bus test cycle. TfL do not operate any methane fuelled buses.However, a brief survey of the literature indicates that other operators and areas are increasingly using ULEV buses. Specific examples include:
- One of the UK’s biggest national bus operators, Arriva, has invested in a new fleet of 174 hybrid buses, with the help of grants from OLEV, the government’s Office for Low Emission Vehicles12 .
- Both Merseytravel and Transport for London were beneficiaries under the £30 million Low Emission Bus Scheme, allowing 123 of the new Volvo diesel-electric hybrid buses to enter service in London, while a further 51 will operate on selected routes around Merseyside12 .
Oxford bus company have recently added 14 brand new hybrid buses which are the very first of a new design by Alexander Dennis (who built the bodies for the 200-series Scanias). They are the first “Euro VI” buses for service in Oxford, and also the first roll-out of the Gyrodrive hybrid power system. (Williams engineering KERS system). This takes the number of hybrids in the Oxford Bus Company’s fleet to 83 out of a fleet of 182 buses and coaches (45.6%)13 ___ 11
Data taken from 2017 source: https://data.london.gov.uk/dataset/number-buses-type-bus-london Non-corroborated data indicates that current non-conventional powertrain fraction has continued to increase 12 See SMMT announcement: https://www.smmt.co.uk/2017/01/major-uk-operator-invests-in-new-hybrid-busfleet/ 13 For announcement about latest additions to Oxford Bus Company’s fleet see https://www.oxfordbus.co.uk/hybrids/.
Statistics taken from October 2018 fleet list, downloaded from https://assets.goaheadbus.com/media/cms_page_media/72/Oxford%20Bus%20Group% 20Current%20Fleet%20List.pdf London, 25.2% English metropolitan areas, 22.6% English nonmetropolitan areas, 39.1% Scotland and Wales, 13.2%
- SPaTS Task 1-650 – Review of updates to emission curves for non-conventional ICE and ultra-low emission vehicles | 20 Ricardo – In confidence Ref: Ricardo/ED11852/ULEV evidence review, Issue 3 Figure 5 Powertrain types for TfL's buses in London Scope in terms of
- The other major operator in Oxford city, Stagecoach, has a lower percentage of hybrids, although that is in the context of a larger fraction of their fleet being coaches that shuttle between Oxford and London14 .
- Reading has adopted a different approach with over half its fleet being ULEV buses, including 31 hybrid buses, and 57 methane fuelled vehicles. These are more than half their total fleet of 168 buses15 . Bids for the provision of methane fuelled buses came from Scania and MAN – indicating companies with commercially available methane buses at the time of tendering. The above references emphasise the importance of ULEV buses in terms of their penetration into the fleet. Combined with these rapid increases in numbers, there has been a rapid collection of data regarding their use. TfL in particular have invested considerable resources into quantifying the environmental impact of the bus powertrain options they use. Detailed measurement campaigns, principally undertaken in collaboration with the VTEC facility at Millbrook Proving Ground, and published high level overviews16 . Another example are case studies published following the introduction of new vehicles (e.g. Reading indicating that their methane fuelled buses lead to a 30 – 50% reduction in NOx emissions relative to comparable diesel technologies)17 . Together these indicate that there is already a strong body of emissions evidence that is available on which emissions curves could be based. Conversations with these operators indicate that they are willing to share, up to a point, data that could be used to generate new emission curves, which, at the same time, promotes their use of these ULEVs. Further avenues for potentially acquiring data include LowCVP’s Bus Working Group, and the OLEV Low Emission Bus scheme where £30 million has been allocated to low emission buses. As for chassis laboratory testing of LDVs, provided that customer confidentiality is preserved, recently collected data could be used for generating new emission curves for these important ULEVs that operate in urban areas.
14 For Stagecoach’s Oxford fleet list see: http://www.ukbuses.co.uk/fleet/stagecoachoxfordshire.pdf 15 Data taken from Reading Buses website: https://www.reading-buses.co.uk/about-us 16 See for example a presentation by F Coyle on “Cutting carbon from the London bus fleet”, https://www.lowcvp.org.uk/assets/presentations/Transport%20for%20London%20- %20Finn%20Coyle.pdf 17 See for example http://www.clean-fleets.eu/fileadmin/files/documents/Publications/Reading_C leanFleets_CaseStudy.pdf Hybrid 30.60% Electric 0.76% Hydrogen 0.10% Conventional 68.53%